![]() ![]() Our species isn’t unique in having a foramen magnum positioned on the undersides of our skulls. These primates are not bipeds like us or some of the other mammals in the study, but, nevertheless, those that hold their bodies upright have a foramen magnum positioned forward of species with different postures. In their sample, Russo and Kirk compared strepsirrhine primates – lemurs, lorises, and galagos – that hold their bodies upright with those that typically keep their spines parallel to the ground. Lemurs and their close relatives, too, throw anatomical support to an upright posture being tied to where the foramen magnum is situated. That goes for us, too – the foramen magnum in the human skull is positioned in a way not seen in any other living ape. While the rodents and marsupials showed some overlap in the position of the foramen magnum between bipedal and quadrupedal species, in general Russo and Kirk found that bipedal species in each group tended to have a more forward-positioned opening. Russo and Kirk examined non-human primates, marsupials, and rodents in their study, comparing bipedal forms – such as kangaroos and wallabies in the case of marsupials – with quadrupedal relatives. If bipedalism and foramen magnum position are linked in these beasts, then there’s likely to be a functional connection for humans, too. sapiens is the only habitually bipedal living primate species,” Russo and Kirk note that habitual bipedalism has evolved independently among mammal groups other than primates. While they point out that “Past attempts to link foramen magnum position with bipedalism specifically have also been complicated by the fact that H. In a new Journal of Human Evolution study, however, anthropologists Gabrielle Russo and Christopher Kirk suggest a way around the impasse. And as researchers William Kimbel and Yoel Rak suggested in a 2010 study, the position of the skull opening may have more to do with the posture of the trunk than walking upright. A connection between the foramen magnum and bipedalism seems right, but there’s not much hard evidence to back up the link. But other researchers have cast doubt on whether this curious skull opening really is a clear indicator of striding about on two legs. ![]() Paleoanthropologist Raymond Dart used the orientation of the hole on the “Taung child” skull of Australopithecus africanus to argue that the fossil represented an early human, and, more recently, Michel Brunet has used the same argument to hypothesize an early human identity for a controversial fossil called Sahelanthropus tchadensis. Not everyone has agreed on the importance of foramen magnum to inferring bipedal habits among hominids. If the foramen magnum indicates the position of the spine in relation to the head, and therefore whether the creature was bipedal or moved about some other way, then the position of the opening might indicate when our ancestors developed the upright, bipedal posture so often taken to be the hallmark of humanity. This bone aperture has taken on great importance in the ongoing investigation into when the human lineage split from those of other apes. The technical name for the opening is the foramen magnum – the “great hole” that the spinal cord and other critical soft tissues run through. On the bottom of your skull, there is a distinctive hole. ![]()
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